Clean up mesh_manager.cpp
Clean up mesh_manager.cpp

evinstk/TantechEngine,evinstk/TantechEngine,evinstk/TantechEngineOriginal,evinstk/TantechEngineOriginal,evinstk/TantechEngineOriginal,evinstk/TantechEngine,evinstk/TantechEngineOriginal,evinstk/TantechEngine,evinstk/TantechEngine,evinstk/TantechEngineOriginal,evinstk/TantechEngine,evinstk/TantechEngineOriginal